The inventive concepts relate to a semiconductor device and, more particularly, to an optical input/output (I/O) device, an opto-electronic system including the same, and a method of manufacturing the same.
Semiconductor devices such as a central processing unit (CPU), a memory device, and a logic circuit of a computer may be mostly integrated on a silicon substrate. Semiconductor chips consisting of such integrated circuits may transmit and receive signals through metal interconnections. However, an interconnecting method using the metal interconnections may cause problems such as reduction of signal processing speeds, generated heat in proportion to a cumulative usage time, and crosstalk. Thus, optical data communication between chips or within a chip based on silicon photonics technology are being demanded in order to realize high performance and high-speed computer systems, high-capacity data communication systems and image processing systems. In order to satisfy future demands, various researches are conducted for silicon photonics technologies for silicon chip-level optical data interconnections.
Generally, silicon optical communication devices developed in the silicon photonics technology are mainly optical waveguide type silicon photonics devices using a silicon-on-insulator (SOI) substrate, not a conventional bulk silicon substrate on which a complementary metal-oxide semiconductor (CMOS) integrated circuit is realized. Currently, silicon optical interconnections based on the waveguide-type silicon photonics devices are being investigated. However, the SOI substrate is expensive compared with the bulk silicon substrate. This is because a buried oxide (BOX) layer should be formed to be near to a surface of a silicon substrate by additional processes when the SOI substrate is manufactured. Due to crystal defects of the substrate caused by the formation of the BOX layer, performance of an electronic device based on the SOI substrate may be deteriorated as compared with performance of an electronic based on a mature and well-established bulk silicon substrate of a conventional art. Additionally, when an opto-electronic convergence chip is manufactured, a manufacturing process of an electronic integrated circuit is changed into techniques based on the SOI substrate such that additional efforts and costs are increased. Also, it may be the same case when optical waveguide-type silicon photonics devices are integrated on a SOI portion locally formed on the bulk silicon substrate. When the local SOI part is formed on the bulk silicon substrate, various additional processes (e.g., a high temperature thermal treatment process) are required, which can deteriorate the performance of an integrated circuit formed on the same bulk silicon substrate. The optical waveguide silicon photonics device formed on the local SOI part may have demerits such as high optical loss and low performance.
A light source for silicon optical input/output (I/O) is based on a III-V compound semiconductor light source. Integration a silicon photonics-based light source may be realized by a hybrid laser, a die-bonding packaging, or a printed circuit board (PCB) module packaging. In the hybrid laser, an optical waveguide-based light source such as a III-V compound semiconductor distributed feedback laser diode (DFB LD) is bonded on the SOI substrate by a wafer bonding technique. In the die-bonding packaging method, a III-V compound semiconductor DFB LD chip is mounted on a SOI-based silicon photonics chip by a flip-chip bonding technique. All of the hybrid laser method and the die-bonding package method should fundamentally use expensive SOI substrates. Thus, productivity of conventional optical I/O devices based on a SOI substrate is low.
Thus, all of electronic circuits and optical components should be realized on the same bulk silicon substrate in order that silicon photonics devices are practically used in silicon integrated circuits. Therefore, there is a need for new optical I/O device structures capable of realizing merits such as high performance, high speed, high efficiency, high-level functionality, low manufacture costs, and low packaging costs.